Projectors, flat panel displays and other video display devices do not always synchronize reliably to input video signals. When a video signal changes, it can force a re-synchronization of a display unit such as a projector or LCD (flat) panel. That synchronization sometimes fails and the display is no longer able to find a video signal. This can be very inconvenient where the display system is used at an event or meeting where high reliability is desired and/or skilled operators may be unavailable. The loss of the video signal is even more likely to occur in a plurality of display units organized in a collection that is synchronized together. Thus, it is desirable to avoid the need to perform a re-synchronization task so as to avoid losing the signal. Additionally, synchronization of video signals is a relatively slow process, and thus avoiding re-synchronization can desirably increase the speed of a display system with one or more display units.
For a display system consisting of one or more display units, there are a variety of techniques for altering the input source video signal to one or more of the display units. For example, adjustments can be made to the signal to vary the displayed image's warp and/or scale, blend, color correction, and/or the pixel overlap/bezel correction change. Likewise, changes can be made to the operating point of the equipment used, which can be termed the optical mechanical thermal and electronic (OMTE) parameters. US published Patent Application No. 20080/246781 A1, entitled SYSTEM AND METHOD FOR PROVIDING IMPROVED DISPLAY QUALITY BY DISPLAY ADJUSTMENT AND IMAGE PROCESSING USING OPTICAL FEEDBACK, by Rajeev J. Surati, et al., the teachings of which are expressly incorporated herein by reference as useful background information, describes the optical mechanical thermal and electronic (OMTE) parameters of a display. The OMTE parameters may be modified under computer or manual control and then an appropriate mapping function may make transformations to the displayed image source signal that work together with the OMTE changes.
A variety of devices and/or modalities can be employed to make changes to the source signal including, but is not limited to, computers, with a driver/software that can perform, a sub-set of corrections to the source signal being created, video wall controllers, warping boxes, scaling boxes, EDID boxes, video wall controllers, and/or the display units (e.g. projectors) themselves. Any of the contemplated devices can be adapted to change the appearance of the final viewed image—desirably to provide a better overall appearance and (where multiple display units are used) consistency across blended images. However, the use of such devices and other alterations to the source signal raises the risk of loss of video synchronization and/or reduced system speed/performance.
The most common time when the system is changed is during calibration. Whether the system is manually, semi-manually or automatically calibrated, the settings are typically changed one or more times.
Sometimes changing the pixel overlap (for example for projectors) or the bezel correction (for flat panels) causes a re-synchronization. Sometimes changing the warp and/or changing the blend can cause a re-synchronization. It is therefore desirable to be able to make changes to the system without causing a display unit to re-synchronize, or to re-synchronize as little as possible.
Another disadvantageous scenario is when an application (e.g. an automated or manual calibration program) desires to reset a parameter, such as overlaps, and may lack access to set this parameter. In such cases the system may continue operating with a poorly set parameter, negatively affecting image quality. The ability to set a parameter overlap once through some other method and eliminate the need to reset said parameter is thus highly desirable.
In addition, it is often desirable to set the input resolution of the display units in the system to essentially match the aspect ratio of the displayed image. This can involve re-synchronization in an effort to achieve the correct resolution, again inviting all the risks and disadvantages to such a state.
Thus, it is highly desirable to avoid re-synchronization, particularly during runtime operation of the display system, and more generally to provide an arrangement that avoids changing parameters that can potentially slow down the calibration process and possibly change the system appearance and/or performance in one or more subtle ways (e.g. providing each unit with slightly different timings, etc.)